Migration 



SPRING 



Swainson's Warblers apparently follow the most direct routes 

 in migrating from wintering to breeding grounds. From West 

 Indian wintering grounds they apparently reach the United 

 States by island-hopping to southern Florida. Birds moving north- 

 ward from eastern Cuba and Jamaica may touch some of the 

 Bahama islands and cays enroute: there are March and April 

 records from Bimini, Andros Island, and Cay Lobos. 



The northern coast of Yucatan is a natural departure point for 

 trans-Gulf flight to the Gulf Coast of the United States. Studies 

 by G. H. Lowery (1945, p. 92-121; 1946, p. 175-211) and H. M. 

 Stevenson (1957, p. 39-77) and observations by several other 

 ornithologists lend credence to a trans-Gulf movement of Swain- 

 son's Warblers from the northern coast of Yucatan and the shore 

 of the Bay of Campeche. The distribution of casualties at the 

 base of the Tall Timbers TV tower near Tallahassee, Fla., 50 

 miles from the Gulf, indicates that the spring flight through that 

 region is mainly in a southwest-to-northeast direction (Stoddard 

 and Norris, 1967, p. 11, 15). Stoddard and Norris believe that this 

 is mainly a trans-Gulf flight, with a minor segment of the flight 

 skirting the Gulf. The lesser migration, which they refer to as the 

 "Florida Peninsula-West Indian Flight" comes through mainly 

 on easterly, southeasterly, and southerly winds. 



It is probable that some of the Swainson's Warblers that winter 

 in eastern Mexico migrate around the Gulf, moving northward 

 along the eastern coasts of Mexico and Texas. The numerous 

 spring records from coastal Texas could represent both trans-Gulf 

 and circum-Gulf migrants. 



Exceptionally early arrivals reach Florida by the middle of or 

 the third week of March. There are records by J. Johnson and 

 D. R. Paulson for March 16 offshore near Eau Gallie and for 

 March 19 at Goulds, south of Miami (Stevenson, 1960, p. 304), 

 and Bush Key pond. Dry Tortugas, March 17, 1964 (Robertson 

 and Mason, 1965, p. 136). The first wave of migrants reaches 

 northern Florida during the last week in March. At Tallahassee, 

 during the period 1956 to 1966, 14 of 83 birds striking the Tall 



22 



